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LAM gene family

Reviewed September 2013

What are the LAM genes?

The LAM gene family comprises genes that provide instructions for making proteins called laminins. These proteins are heterotrimers, which means they are made of three different parts (subunits). Every laminin protein is composed of a heavy alpha subunit and two lighter subunits designated beta and gamma. There are several forms of each subunit, and each form is produced from instructions carried by a different gene. At least five alpha subunits, four beta subunits, and three gamma subunits have been identified.

Laminins are found in an intricate lattice of proteins and other molecules that forms in the spaces between cells (the extracellular matrix). There, they help regulate cell growth, cell movement (motility), and the attachment of cells to one another (adhesion). They are also involved in the formation and organization of basement membranes, which are thin, sheet-like structures within the extracellular matrix that separate and support cells in many tissues.

Individual laminin proteins are often located in particular tissues. For example, laminin 2 and laminin 4 are found primarily in muscles used for movement (skeletal muscles). Gene mutations that affect the structure or availability of these laminins can result in muscular dystrophy, a group of disorders characterized by muscle weakness and wasting. Laminin 5 plays an important role in the basement membrane beneath the top layer of skin (the epidermis); this membrane gives the skin strength and resiliency and creates an additional barrier between the body and its surrounding environment. Mutations in genes that provide instructions for making laminin 5 subunits can lead to fragile skin that easily breaks down.

Which genes are included in the LAM gene family?

The HUGO Gene Nomenclature Committee (HGNC) provides an index of gene families (http://www.genenames.org/cgi-bin/genefamilies/) and their member genes.

Genetics Home Reference summarizes the normal function and health implications of these members of the LAM gene family: LAMA2, LAMA3, LAMB3, and LAMC2.

What conditions are related to genes in the LAM gene family?

Genetics Home Reference includes these conditions related to genes in the LAM gene family:

amelogenesis imperfecta

junctional epidermolysis bullosa

LAMA2-related muscular dystrophy

laryngo-onycho-cutaneous syndrome

What glossary definitions help with understanding the LAM gene family?

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healthcare professional.
See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.